I'm imagining a scenario in which this guy is walking around, asking random people for a kidney, until one day he asks a guy who says, "Oh yeah, hold on one sec" and pulls one out of the trunk of his car in a cooler or something.

If I had a life-threatening kidney disease and no one in my family was a suitable match, I'd like to think my wife would do the same for me. In reality, she'd probably just try to sell all my stuff on Craigslist and convert my home office into a yoga studio.